Semiconductor sensor having a suspended structure and method of forming a semiconductor sensor having a suspended structure

Abstract

A semiconductor gas sensor device includes a substrate, a conductive layer supported by the substrate, a non-suitable seed layer, and a porous gas sensing layer portion. The non-suitable seed layer is formed from a first material and includes a first support portion supported by the conductive layer, a second support portion supported by the conductive layer, and a suspended seed portion extending from the first support portion to the second support portion and suspended above the conductive layer. The porous gas sensing layer portion is formed from a second material and is supported directly by the non-suitable seed layer in electrical communication with the conductive layer. The first material and the second material form a non-suitable pair of materials.

What is claimed is: 
     
       1. A semiconductor gas sensor device comprising:
 a substrate; 
 a conductive layer supported by the substrate; 
 a non-suitable seed layer formed from a first material and including a first support portion supported by the conductive layer, a second support portion supported by the conductive layer, and a suspended seed portion extending from the first support portion to the second support portion and suspended above the conductive layer, and 
 a porous gas sensing layer portion formed from a second material and supported directly by the non-suitable seed layer and in electrical communication with the conductive layer, the first material and the second material forming a non-suitable pair of materials, 
 wherein the porous gas sensing layer portion is in direct contact with the conductive layer. 
 
     
     
       2. The semiconductor gas sensor device of  claim 1 , wherein:
 the suspended seed portion defines a lower surface adjacent to the conductive layer and an opposite upper surface; 
 a first portion of the porous gas sensing layer portion is supported directly by the lower surface; and 
 a second portion of the porous gas sensing layer portion is supported directly by the upper surface. 
 
     
     
       3. The semiconductor gas sensor device of  claim 1 , wherein:
 a first isolated portion of the conductive layer is electrically isolated from a second isolated portion of the conductive layer; 
 the first support portion extends from the first isolated portion; and 
 the second support portion extends from the second isolated portion. 
 
     
     
       4. The semiconductor gas sensor device of  claim 1 , wherein:
 the porous gas sensing layer portion defines a suspended sensing portion that is supported directly by the suspended seed portion; and 
 the suspended sensing portion defines a substantially “U”-shaped cross-section in a plane perpendicular to the substrate. 
 
     
     
       5. The semiconductor gas sensor device of  claim 1 , wherein:
 the porous gas sensing layer portion defines a suspended sensing portion that is supported directly by the suspended seed portion; and 
 the suspended sensing portion defines a substantially serpentine configuration. 
 
     
     
       6. The semiconductor gas sensor device of  claim 1 , wherein the porous gas sensing layer portion is configured to exhibit a change in at least one of a resistance, a capacitance, and a resonant frequency in the presence of a target gas. 
     
     
       7. The semiconductor gas sensor device of  claim 1 , wherein:
 the first material is silicon dioxide, and 
 the second material is platinum. 
 
     
     
       8. A method of fabricating a semiconductor gas sensor device comprising:
 forming a conductive layer above a substrate; 
 patterning the conductive layer to define a first isolated portion of the conductive layer that is electrically isolated from a second isolated portion of the conductive layer; 
 forming a sacrificial layer above the conductive layer; 
 patterning the sacrificial layer to define a first trench portion exposing an upper surface of the first isolated portion, a second trench portion exposing an upper surface of the second isolated portion, and a suspended trench portion that does not expose the conductive layer and that extends from the first trench portion to the second trench portion; 
 forming a non-suitable seed layer from a first material in the first trench portion, the second trench portion, and the suspended trench portion; 
 forming a porous gas sensing layer portion from a second material on the non-suitable seed layer and in electrical communication with the conductive layer, the second material deposited into the first trench portion, the second trench portion, and the suspended trench portion, and the first material and the second material forming a non-suitable pair of materials; and 
 removing the sacrificial layer to suspend a suspended portion of the seed layer and the porous gas sensing layer portion above the conductive layer. 
 
     
     
       9. The method of  claim 8 , wherein forming the non-suitable seed layer comprises:
 depositing the first material onto the sacrificial layer using atomic layer deposition, 
 wherein the first material is aluminum oxide. 
 
     
     
       10. The method of  claim 9 , wherein forming the porous gas sensing layer portion comprises:
 depositing the second material onto the non-suitable seed layer using atomic layer deposition, 
 wherein the second material is platinum. 
 
     
     
       11. The method of  claim 8 , wherein patterning the sacrificial layer comprises:
 trenching the suspended trench portion into a substantially serpentine configuration. 
 
     
     
       12. The method of  claim 8 , wherein patterning the sacrificial layer comprises:
 trenching the suspended trench portion into a substantially rectangular configuration. 
 
     
     
       13. The method of  claim 8 , further comprising:
 forming an insulator layer above the substrate; and 
 forming the conductive layer above the insulating layer.